1. Technical Field
The present invention relates to a liquid crystal display and an electronic apparatus.
2. Related Art
For liquid crystal displays, vertical electric field methods, such as a TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, and MVA (Multi-domain Vertical Alignment) mode, are widely used. However, lateral electric field methods are also known where the liquid crystal display includes the electrode only in one of the substrates. Among liquid crystal displays using the lateral electric field methods, the principle of operation for a liquid crystal display having an FFS mode is described with reference to FIG. 12 and FIG. 13 (see, for example, JP-A-2001-56476).
FIG. 12 is a schematic plan view of one pixel which is perspectively represented through a color filter substrate CF of a liquid crystal display 190 having an FFS mode used as an example in the related art. FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. 12.
The liquid crystal display 190 having an FFS mode includes an array substrate AR and a color filter substrate CF. The array substrate AR is provided with a plurality of scan lines 194 and a common interconnection 196 which are each parallel to a surface of a first transparent substrate 192, and provided with a plurality of signal lines 198 in a direction intersecting with these scan lines 194 and the common interconnection 196. And then, an opposite electrode (also referred to as a “common electrode”) 200, formed of a transparent material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) connected to the common interconnection 196, is provided so as to cover each of the regions partitioned by the scan lines 194 and the signal lines 198. A pixel electrode 206, composed of a transparent material such as ITO in which a plurality of slits 204 is formed in the form of stripes, is provided in a surface of the opposite electrode 200 via an insulating film 202. Surfaces of the pixel electrode 206 and the plurality of slits 204 are coated by an oriented film 208.
A TFT, used as a switching element, is formed in the vicinity of the position in which the scan lines 194 intersects with the signal lines 198. The TFT is constituted so that a semiconductor 210 is disposed on a surface of the scan lines 194, a portion of the signal lines 198 extends to form a source electrode S in order to cover a portion of the surface of the semiconductor 210, and the scan line portion of a lower section of the semiconductor 210 forms a gate electrode G. In addition, the TFT is constituted so that a conductive layer overlapping with a portion of the semiconductor 210 forms a drain electrode D and the drain electrode D is connected to the pixel electrode 206.
In addition, the color filter substrate CF is constituted so that a color filter layer 214, an overcoat layer 216, and an oriented film 218 are disposed on a surface of a second transparent substrate 212. The array substrate AR and the color filter substrate CF are made opposite to each other so that the pixel electrode 206 and the opposite electrode 200 of the array substrate AR and the color filter layer 214 of the color filter substrate CF are opposed to each other. Next, a liquid crystal LC is sealed between the array substrate AR and the color filter substrate CF, and polarizing plates 220 and 222 are disposed in each of external sides of both substrates in order to be in the direction which makes polarizing directions thereof orthogonal to each other, so that the liquid crystal display 190 having an FFS mode is formed.
When an electric field arises between the pixel electrode 206 and the opposite electrode 200 in the liquid crystal display 190 having an FFS mode, as shown in FIG. 13, this electric field faces toward the opposite electrode 200 on both sides of the pixel electrode 206. Therefore, liquid crystals existing on the pixel electrode 206 as well as liquid crystals existing in the slit 204 can move.
However, a liquid crystal display having an FFS mode has a drawback in that it is difficult for the liquid crystal molecules between electrodes or on electrodes to twist depending on the strength or weakness of the electric field intensity, thereby lessening the brightness of a display.
Moreover, a liquid crystal display having an FFS mode has a problem in that it is necessary to form a lower electrode width with good accuracy and that an exposure margin is narrow, since a lower electrode is formed to be slightly wider than an upper electrode and be in a linear fashion. Therefore, the V-T characteristics can vary to a great extent due to a slight exposure deviation, and the brightness may be greatly lowered in extreme cases.